Redirecting carbon flux in Torulopsis glabrata from pyruvate to α-ketoglutaric acid by changing metabolic co-factors

The nutrition conditions needed to redirect the carbon flux in Torulopsis glabrata, a pyruvate hyper-production yeast, from pyruvate to alpha-ketoglutaric acid (KG) were investigated in a stirred fermentor. A minor amount of KG (1.3 gl(-1)) was produced when NaOH was used to control the pH, while 12 g KG l(-1) was produced when CaCO3 was used instead. When thiamine and biotin were included in the medium, 13 g KG l(-1) and 68 g pyruvate l(-1) were produced after 48 h when glucose was nearly consumed (approximately 5 gl(-1)). With fermentation continuing for a further 16 h, the concentration of pyruvate decreased to 31 gl(-1), and KG increased to 30 gl(-1). KG thus accumulated at the expense of pyruvate consumption.